Until recently, tracking people with Global Positioning System technology required purchasing expensive hardware and software. Now, complete solutions are available through cellular service providers. Here is background info and a few options for keeping up with the whereabouts of your family, friends and employees.

Locating People in an Emergency
Stimulated by the events of 11 September 2001, the demand for enhanced 911 (e911) emergency calling capabilities, pushed forward GPS tracking technology in cell phones. At the end of 2005, all cell phone carriers were required to provide the ability to trace cell phone calls to a location within 100 meters or less.

To comply with FCC requirements, cell phone carriers decided to integrate GPS technology into cell phone handsets, rather than overhaul the tower network. However the GPS in most cell phones are not like those in your handy GPS receiver that you take hiking. Most cell phones do not allow the user direct access to the GPS data, accurate location determination requires the assistance of the wireless network, and the GPS data is transmitted only if a 911 emergency call is made.

So, in general, you can not track someone using their cell phone, unless the person you want to track has the right kind of cell phone, connected to the right network, with the right service.

GPS-enabled Cell Phones:
Motorola and Blackberry were the first GPS-enable phones to proliferate the United States. Initially, Motorola"iDEN" phones were commonly used for employee tracking on the business-oriented Nextel network. Then GPS enabled Blackberry phones, once used almost exclusively by corporate and government VIPs, began to penetrate the consumer market stimulated by the demand for phones with advanced messaging capability. Next came specialty devices produced under the names of "Disney Mobile" and "Wherify Wireless" targeting use by children and elderly. Now in 2009, a variety of GPS-enabled phones and tracking services are available, as you can see from the ads on this page.

Wireless Networks
Your phone may have GPS and "know" exactly where it is, but it can't "tell" anyone else where you are unless you are connected to a wireless network. Here in the United States, the wireless networks used for GPS tracking are primarily those operated by cell phone carriers. It is not likely that you as an individual will negotiate network access with a carrier. It is more likely that you will select a solution including a cell phone provisioned to communicate in a certain way on a specific wireless network. List below are a some carriers I recomend for use with GPS cell phones and services.

It is important to note that Wi-fi complements the cellular grid, providing additional conduits for location information to pass through to the net'. Your phone has a unique electronic identifier and - if enabled - can pass this information, locating you within the geographic area covered by the hotspot. There should be little doubt that the vast radioscape of urban environments is being mapped and your participation in services like Google Latitude improve their ability to locate you out of cell range and hidden from GPS satellites. Always read the terms of service before deciding to agree.